The purposes are to determine in the intact dog kidney the relative proportions of citrate oxidized to CO2 and of CO2 formed from citrate in chronic metabolic acidosis and alkalosis. Anesthetized dogs are surgically prepared for obtaining samples of arterial and renal venous blood, urine, and renal cortex during i.v. infusion of 50 microcuries of C14-C6-citric acid. Glomerular filtration rate and renal blood flow are measured. Concentration of citric acid is determined enzymatically and CPM, by separation of citric acid using column chromatography and counting of the eluent in a liquid scintillation flow counter. Total CO2 and CPM in CO2 are also measured. Calculations include S.A. of citrate, CPM/min of citrate removed by the kidney and of CO2 produced by the kidney; ratios of S.A. of citrate in arterial blood/renal venous blood and in arterial plasma/urine. From these we can obtain information on the effects of acidosis and alkalosis on the rates of renal citrate oxidation and production as well as on the proportion of CO2 produced by the kidney from citrate. The long term goals of this type of study are to gain understanding of the mechanisms of the metabolic adaptations of the kidney to alterations of the acid-base balance of the body.